On the 3rd, the first trading day after the U.S. airstrike on Iran, domestic financial markets broadly weakened, taking a direct hit. The KOSPI plunged more than 7%, and the won·dollar exchange rate jumped by over 26 won at once to 1,466 won.

That day, the KOSPI closed at 5,791.91, down 452.22 points (7.24%) from the previous session. By points, the decline was the largest on record; by percentage, it was the worst since ‘Black Monday’ on August 5, 2024, when the KOSPI tumbled more than 8%. U.S. stocks finished slightly higher, but subsequent news that Iran would control the Strait of Hormuz spread geopolitical risk fears and dragged the KOSPI lower.

The KOSDAQ also finished weak at 1,137.70, down 55.08 points (4.62%) from the previous session.

Concerns over inflation, heightened by rising oil prices, also delivered a shock as they fed into dollar strength and higher government bond yields. In the Seoul foreign exchange market, the won·dollar exchange rate closed for the day at 1,466.1 won per dollar, up 26.4 won from the previous session. The increase in the rate was the largest in 11 months, since April 7 last year.

On the KOSPI, the blow was heavy for large-cap stocks that had surged until recently. Blue chips including Samsung Electronics, SK hynix, Hyundai Motor, SK Square, and Doosan Enerbility all plunged more than 9%, pulling the index down. As foreign investors dumped more than 5 trillion won, the slide steepened. The KOSDAQ, which had turned higher intraday and rose over 1%, reversed lower again in the afternoon and sank more than 4%.